Professor Jason Box, from the Geological Survey of Denmark and Greenland who is a co-author of the research, said: "Freshwater coming off the melting Greenland ice sheet is likely disturbing the circulation."

Freshwater is less dense than salty water and less likely to sink, thereby sabotaging the "conveyor" mechanism.

Mr Rahmstorf added: "It is conspicuous that one specific area in the North Atlantic has been cooling in the past hundred years while the rest of the world heats up.

"Previous research had already indicated that a slowdown of the so-called Atlantic meridional overturning circulation (AMOC) might be to blame for this.

"Now we have detected strong evidence that the global conveyor has indeed been weakening in the past hundred years, particularly since 1970."

The scientists used multiple proxy data measurements to show that weakening of the AMOC after 1975 had been at a level unprecedented since the year 900.

They concluded: "Further melting of Greenland in the coming decades could contribute to further weakening of the AMOC."